What to do with that overgrown Norfolk Island pine

Photo of Norfolk Island Pine by Lee Reich

Cold has yet to throw a wrench into salads fresh from the garden, even though December 16 saw a nighttime low of 12 degrees Fahrenheit. Yes, the lettuce would be mush if unprotected; but under the sheltering clear plastic and wooden sides of my five-foot-square coldframe, the plants are barely scathed. Just a few leaves wilted at their edges. Spinach that I sowed between the lettuce plants, for harvest after the lettuce is finished, is still looking spry.

Plastic tunnels supported by wire hoops are offering almost as much cold protection over three garden beds. Beneath them, mustard greens, endive and arugula don’t exactly thrive, but do survive.

A few fresh greens are even surviving out in the garden without any sort of protection whatsoever. That would include some arugula that was never covered, as well as kale – what’s left of it – and mâche, the most cold-hardy of all salad greens.

Once temperatures plummet or the ground is blanketed with snow, fresh salads will come from the greenhouse – which, with night temperatures never allowed to drop below 37 degrees, is packed with lush greenery as if it were May.

Update: Lettuce in the coldframe is flagging after a nighttime low of eight degrees a few days after that 12-degree low. Unprotected out in the garden, only mâche and kale survive.

 

The holiday tree, only a half a foot tall and ornamented with three silver balls, is cute as a button. It’s a Norfolk Island pine (Araucaria heterophylla), a free gift that I received a couple of weeks ago from a mail-order nursery. This tree will green up the darkest days of the year for year after year, because it’s a tropical species that does well in the eternal warmth and somewhat-dry air – in winter, at least – of any home.

Over the years, the tree will lose its impishness and develop a straight, upright trunk, off which will grow relatively widely spaced, whorled tiers of horizontal branches, all clothed in green needles. With age, the plant becomes quite majestic – too majestic, in fact, for any home. I have seen the spreading branches of this tree towering 40 feet or more over the tiled roofs of homes in tropical climates.

So what’s a gardener to do with such a plant, after years of nurturing it and watching it grow? One option, of course, is to bite the bullet and walk it over to the compost pile. Or it could be gifted to a friend with a higher ceiling; but that just shifts responsibility and puts off the inevitable. How about giving it to Grandma for her front lawn in Florida?

A natural inclination for any real gardener in this situation would be to try to keep the plant going – not as its original self, but in the form of a cutting. The rooted cutting, then, is genetically the same as the original plant, only a smaller version. Norfolk Island pine does root from cuttings – especially, as with many conifers, if the cuttings are taken from young growth.

This plan has one problem: fixed plagiotropism. This botanical mouthful signifies the tendency for a horizontal shoot of certain plants always to retain its horizontal growth habit. Put more simply, if a cutting is rooted from one of a Norfolk Island pine’s horizontal stems, that stem will always grow sideways to creep along a windowsill or wherever else the plant is growing.

The solution to this problem is to take a cutting from the leading upright stem. If the mother plant isn’t destined for composting, though, cutting out that leading stem does ruin its form. Also, because young cuttings root best, you might end up with only one cutting, perhaps two, from that short length of young leading stem: not much insurance for a plant that doesn’t root all that easily.

The leading upright stem of a plant can have the opposite inclination: fixed orthotropism, a permanent upright growth habit. With other plants, their plagiotropism or orthotropism may be temporary. Not so for Norfolk Island pine’s plagiotropism. I’ll figure out how to cross that plagiotropic bridge, or not, when I come to it.

For further discussion of topophysis – which encompasses plagiotropism and orthotropism – and related topics on plant growth, see Plant Form: An Illustrated Guide to Flowering Plant Morphology by Adrian Bell and Alan Bryan.

 

Any gardening questions? E-mail them to me at [email protected] and I’ll try answering them directly or in this column. Check out my garden’s blog at https://www.leereich.blogspot.com.

 

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